DRY EYE is a disorder of the ocular surface, caused by multiple factors, featuring a loss of homeostasis of the tear film. It is accompanied by ocular symptoms, where instability and hyperosmolarity of the tear film, inflammation and lesions of the ocular surface and neurosensory anomalies, play an important role in the aetiology of the disorder.
The symptoms are burning, pricking pain, itching, feeling of an external body, dryness, tiredness of the eyes and eyelids, photophobia, blurred vision.
The following anatomical and physiological factors help to maintain the surface of the eye unaffected:
– a normal quantity of tear fluid;
– normal composition of tear fluid;
– regular blinking to evenly distribute tear fluid.
Tears are therefore very important for keeping the eye healthy. As well as having an antibacterial role, they lubricate the eye surface and protect it from any foreign bodies.
Other factors such as atmospheric and environmental pollution, lifestyle (computer screens), the presence of allergens (i.e. potentially irritating substances) and extended use of contact lenses, can reduce the production of tears. Also, meibomian gland dysfunction with lipid layer deficit are also a cause of dry eye.